Umbrellas are used all the year round and are indispensable to every household but disadvantages still exist in the conventional umbrellas which can be classified into the two following kinds:
1. Manual umbrellas: This kind of umbrellas making use of springs and snap catches is folded and unfolded by two hands. It is often the case that the user's fingers are injured by the snap catch. It is not only difficult but also more dangerous for children to use.
2. Automatic umbrellas: This kind of umbrellas also makes use of springs and snap catches but has a release button. The umbrella will be unfolded automatically when the release button is depressed. But the sudden unfolding often tends to make a noise and cause damage to the umbrella. The odds are that it injures the bystanders when being unfolded. Furthermore, it also needs two hands to fold the umbrella.
Since both kinds of umbrellas make use of springs, the natural elastic fatigue will result in failure of the umbrella. In view of these disadvantages, the inventor worked hard to make improvement and developed this invention.
So the main object of this invention is to provide a pneumatic umbrella which comprises a barrel in three sections, a piston fitted in the barrel and connected to a sliding hub, and a cone, that work together to unfold or fold the umbrella so that the umbrella can be operated by one hand.
Another object of this invention is to provide a pneumatic umbrella which has a throttle valve installed at the bottom of the middle section of the barrel to control the air flow between the upper and lower compressing chambers.
Still another object of this invention is to provide a pneumatic umbrella which has a plunger connected with a rod to the knob at the bottom cap of the barrel and having an air passage through the rod and knob for releasing the air when the air release button at the knob is depressed to collapse the barrel one section inside another.
Still another object of this invention is to provide a pneumatic umbrella of which the plunger rod has an oblong plate pushed against the bottom of the middle section, which has a corresponding oblong hole, by a tension spring fitted over the rod between the plunger and the oblong plate so that the spring can provide a force of return when the lower section of the barrel moves up to compress the air in the lower compressing chamber.